In recent years, use of an RFID (Radio Frequency Identification) tag using a semiconductor chip capable of reading and writing information is expanding for information management and distribution management of articles.
The RFID tag includes an IC chip having a memory for recording information, an antenna for transmitting information which is recorded in the memory of the IC chip by radio and for receiving information and power transmitted, and a base material on which the antenna is mounted. Since the information recorded in the IC chip can be communicated to a reader/writer, the information recorded in the IC chip can be read in a non-contact state by the reader/writer. And, information can be reversely written into the IC chip.
For a UHF (Ultra High Frequency) band or SHF (Super High Frequency) band antenna of the RFID tag, a belt-like dipole antenna is mainly used. For example, this antenna is formed by forming a conductor into a rectangular plate shape or coating a conductor of an Ag paste onto the base material. Here, the antenna is formed with an L shape slit having an impedance matching mechanism for performing impedance matching between the antenna and the IC chip.
The IC chip of the RFID tag can also be provided with a congestion control function capable of collectively reading plural RFID tags by a reader apparatus. Thus, there are cases that plural documents to which the RFID tags are attached are managed collectively.